Article reposted with permission from Wasted Space

The Parking Reform Network recently released their new parking lot map. The interactive map displays the area of city centers and downtowns dedicated to off street parking. Across the 50 city centers analyzed, 20% of the area within the boundaries are dedicated to parking. This is valuable urban land that, if developed differently, could improve walking access and supply much needed housing, while simultaneously reducing paved surface that contributes to urban heat. The research below takes this approach and applies it across the entire city of Portland.

Portland, Oregon is known for being green, walkable and a leader in parking reform. Even though most developments do not require parking today, a long legacy of parking mandates are still visible in the city.  This research seeks to understand how much of the city is used for off street parking.

By using GIS software, this research maps all parking lots and off street asphalt areas within the administrative boundaries of the city of Portland. In the program QGIS, satellite images from Google were manually scanned and all parking lots were traced as polygons. Area of the polygon and their zoning information was collected. This research is limited to surface parking and does not include parking garages.

The results show that Portland has 27.6 sq miles of parking lot and off street asphalt area. That’s 19% of the total area of the city. The median parking lot in Portland is about 14,000 square feet, or about three standard (50ft x 100ft) lots. The average parking lot is significantly bigger at 55,000 square feet, which equates to 11 standard lots, or about one and a half city blocks. That means the typical lot in Portland has around 30 to 120 parking spaces. Citywide there is space for 1.69 million cars to park off street, which amounts to 2.6 off street parking spaces per person, or roughly 5 per household. This estimate does not include the number of parking spaces available in residential driveways, garages, parking structures or any on street parking within the city.

Looking at the land use of these parking lots, we see that the heavy industrial zones, IH and IG2, account for 50.4% of all parking and asphalt area. In total, industrial land uses (EG1, EG2, EX, IG1, IG2, IH) account for 60.2% of all parking and asphalt surface. 15.8% of total parking lots are zoned for residential uses (RMP, R20, R10, R7, R5, R2.5, RM1, RM2, RM3, RM4), 13.8% are zoned for mixed use (CM1, CM2, CM3, CR, CX), 8.9% are zoned as open space and 1.4% are zoned for commercial use (CL, CL1, CL2).

In Portland, a residential development does not need to provide parking if it is less than 30 units or it is within 1000 feet of transit. The city has 8.3 square miles of parking lots that are currently zoned to allow for residential uses and, thus, could be developed into housing. Since parking is not required for much of this area it’s possible to convert these parking lots into residential and mixed use buildings. This would be difficult or impossible in cities that still require parking.

Areas with concentrations of parking represent areas with concentrations of destinations. By concentrating people instead of cars in these areas, cities can begin to act on climate and housing goals simultaneously. Converting parking lots to housing creates climate resilience by removing asphalt surfaces that contribute to urban heat while also reducing vehicle miles traveled and thus, emissions. A portion of these buildings that replace parking lots will have green roofs, which help with onsite water management and, again, reduced urban heat.

Portland is experiencing a housing crisis at levels never seen before. For the situation to get any better the city needs to increase access to housing. One way to do this is to build as much housing as possible. This research found that only 18% of the city’s surface parking area could be developed to provide housing. But developing that 18% could provide homes to 727,000 people.